In February 2018, the Inter-American Court of Human Rights (IACHR) published a landmark advisory opinion (OC-23/17) on state obligations in relation to the environment. The opinion concerned the protection and guarantee of the rights to life and to personal integrity under Articles 4(1) and 5(1) of the American Convention on Human Rights (ACHR). The author illustrates and critically examines the Court’s core judicial findings. Besides general remarks on the advisory opinion’s background, the article provides a short résumé of the IACHR’s admissibility considerations. It then explores the IACHR’s latest findings on the interrelation between the environment and human rights, with special emphasis on the “right to a healthy environment”. In particular, the article sheds light on the Court’s innovative concept of extraterritorial application of the ACHR in environmental scenarios and the transfer of principles to human rights law originally rooted in international environmental law, such as the principles of prevention and precaution. Furthermore, the article presents the IACHR’s interpretation of the ACHR in the light of the intergovernmental obligation to cooperate. Finally, it elaborates on the procedural duties the Court imposes on member states, including access to information, participation and access to justice.